@Hatty ...

been playing around and tweaking stuff in firefox this past week and also played with tha add-on you linked to for the tree tabs. thought it was pretty cool but didnt play too nice with my theme and the auto bookmarks hider. when i hovered / activated the tree tabs, my bookmarks toolbar would drop down! LOLOL!!!

(inspired by a screenshot that Scott sent me the other day while we worked on something else)

thanks Hat!
as far as the space gained, really most of it comes from the autobookmarks hider and the compact menu. the other stuff is just eye candy for the most part.
now 'till i find something else to obsess over and tweak. LOL!

fastdial is pretty cool. useful in the sense that you have all your favorite links available as soon as the browser opens up and the fact that its customizable - use your own images for backgrounds / make your own icons if you'd like - as i did. the icons themselves (the thumbs) are also re-sizeable.

and folders. you can add as many folders as youd like. see the screenshot above - this little bit ....

this is a folder that will take me to another set of shortcuts ....

cant say how it compares to the ff built-in feature cause i never used it though.